Department of Molecular and Cellular Biology, University of Guelphgrid.34429.38, Guelph, Ontario, Canada.
Mass Spectrometry Facility, University of Guelphgrid.34429.38, Guelph, Ontario, Canada.
mSystems. 2022 Jun 28;7(3):e0015622. doi: 10.1128/msystems.00156-22. Epub 2022 May 12.
Epidemic strains of Pseudomonas aeruginosa are highly virulent opportunistic pathogens with increased transmissibility and enhanced antimicrobial resistance. Understanding the cellular mechanisms behind this heightened virulence and resistance is critical. Peptidoglycan (PG) is an integral component of P. aeruginosa cells that is essential to its survival and a target for antimicrobials. Here, we examined the global PG composition of two P. aeruginosa epidemic strains, LESB58 and LESlike1, and compared them to the common laboratory strains PAO1 and PA14. We also examined changes in PG composition when the strains were cultured under nutrient conditions that resembled cystic fibrosis lung infections. We identified 448 unique muropeptides and provide the first evidence for stem peptides modified with O-methylation, -diaminopimelic acid (DAP) deamination, and novel substitutions of DAP residues within P. aeruginosa PG. Our results also present the first evidence for both d,l- and l,d-endopeptidase activity on the PG sacculus of a Gram-negative organism. The PG composition of the epidemic strains varied significantly when grown under conditions resembling cystic fibrosis (CF) lung infections, showing increases in O-methylated stem peptides and decreases in l,d-endopeptidase activity as well as an increased abundance of de-N-acetylated sugars and l,d-transpeptidase activity, which are related to bacterial virulence and antibiotic resistance, respectively. We also identified strain-specific changes where LESlike1 increased the addition of unique amino acids to the terminus of the stem peptide and LESB58 increased amidase activity. Overall, this study demonstrates that P. aeruginosa PG composition is primarily influenced by nutrient conditions that mimic the CF lung; however, inherent strain-to-strain differences also exist. Using peptidoglycomics to examine the global composition of the peptidoglycan (PG) allows insights into the enzymatic activity that functions on this important biopolymer. Changes within the PG structure have implications for numerous physiological processes, including virulence and antimicrobial resistance. The identification of highly unique PG modifications illustrates the complexity of this biopolymer in Pseudomonas aeruginosa. Analyzing the PG composition of clinical P. aeruginosa epidemic strains provides insights into the increased virulence and antimicrobial resistance of these difficult-to-eradicate infections.
铜绿假单胞菌的流行株是高度毒力的机会性病原体，具有更高的传染性和增强的抗微生物耐药性。了解这种高毒力和耐药性背后的细胞机制至关重要。肽聚糖 (PG) 是铜绿假单胞菌细胞的一个组成部分，对其生存至关重要，也是抗微生物药物的靶标。在这里，我们研究了两种铜绿假单胞菌流行株 LESB58 和 LESlike1 的全局 PG 组成，并将其与常见的实验室菌株 PAO1 和 PA14 进行了比较。我们还研究了在类似于囊性纤维化肺部感染的营养条件下培养时，PG 组成的变化。我们鉴定了 448 个独特的肽聚糖，并首次提供了关于 O-甲基化、-二氨基庚二酸 (DAP) 脱氨和新型 DAP 残基取代的铜绿假单胞菌 PG 茎肽的证据。我们的结果还首次提供了革兰氏阴性菌 PG 被囊上 d,l-和 l,d-内肽酶活性的证据。当在类似于囊性纤维化 (CF) 肺部感染的条件下生长时，流行株的 PG 组成差异显著，表现为 O-甲基化茎肽增加，l,d-内肽酶活性降低，以及去 N-乙酰化糖和 l,d-转肽酶活性增加，分别与细菌毒力和抗生素耐药性相关。我们还确定了菌株特异性变化，其中 LESlike1 增加了茎肽末端的独特氨基酸添加，而 LESB58 增加了 amidase 活性。总体而言，这项研究表明，铜绿假单胞菌 PG 组成主要受模仿 CF 肺部的营养条件影响，但菌株间也存在固有差异。使用肽聚糖组学检查肽聚糖 (PG) 的全局组成可以深入了解作用于这种重要生物聚合物的酶活性。PG 结构的变化对包括毒力和抗微生物耐药性在内的许多生理过程有影响。高度独特的 PG 修饰的鉴定说明了铜绿假单胞菌中这种生物聚合物的复杂性。分析临床铜绿假单胞菌流行株的 PG 组成可以深入了解这些难以根除的感染的增加的毒力和抗微生物耐药性。
